/*******************************************************************************************
*
*   raylib [shaders] example - Simple shader mask
*
*   This example has been created using raylib 2.5 (www.raylib.com)
*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
*
*   Example contributed by Chris Camacho (@codifies -  http://bedroomcoders.co.uk/) 
*   and reviewed by Ramon Santamaria (@raysan5)
*
*   Copyright (c) 2019 Chris Camacho (@codifies) and Ramon Santamaria (@raysan5)
*
********************************************************************************************
*
*   The shader makes alpha holes in the forground to give the apearance of a top
*   down look at a spotlight casting a pool of light...
* 
*   The right hand side of the screen there is just enough light to see whats
*   going on without the spot light, great for a stealth type game where you
*   have to avoid the spotlights.
* 
*   The left hand side of the screen is in pitch dark except for where the spotlights are.
* 
*   Although this example doesn't scale like the letterbox example, you could integrate
*   the two techniques, but by scaling the actual colour of the render texture rather
*   than using alpha as a mask.
*
********************************************************************************************/

#include "raylib.h"
#include "raymath.h"

#include <stddef.h>
#include <stdint.h>

#if defined(PLATFORM_DESKTOP)
    #define GLSL_VERSION            330
#else   // PLATFORM_RPI, PLATFORM_ANDROID, PLATFORM_WEB
    #define GLSL_VERSION            100
#endif


#define MAXSPOT           3	// NB must be the same as define in shader
#define numStars        400


// Spot data
typedef struct {   
    Vector2 pos;
    Vector2 vel;
    float inner;
    float radius;
    
    // Shader locations
    unsigned int posLoc;
    unsigned int innerLoc;
    unsigned int radiusLoc;
} Spot;

// Stars in the star field have a position and velocity
typedef struct Star {
    Vector2 pos;
    Vector2 vel;
} Star;

void UpdateStar(Star *s);
void ResetStar(Star *s);

int main(void)
{
    // Initialization
    //--------------------------------------------------------------------------------------
    const int screenWidth = 800;
    const int screenHeight = 450;

    InitWindow(screenWidth, screenHeight, "raylib - shader spotlight");
    HideCursor();

    Texture texRay = LoadTexture("resources/raysan.png");
    
    Star stars[numStars] = { 0 };

    for (int n = 0; n < numStars; n++) ResetStar(&stars[n]);

    // Progress all the stars on, so they don't all start in the centre
    for (int m = 0; m < screenWidth/2.0; m++) 
    {
        for (int n = 0; n < numStars; n++) UpdateStar(&stars[n]);
    }

    int frameCounter = 0;


       
    // Use default vert shader
    Shader spotShader = LoadShader(0, FormatText("resources/shaders/glsl%i/spotlight.fs", GLSL_VERSION));
    
	// Get the locations of spots in the shader
	Spot spots[MAXSPOT];
/*
    unsigned int posLoc;
    unsigned int innerLoc;
    unsigned int radiusLoc;
*/    
    for (int i = 0; i < MAXSPOT; i++) 
    {
		char posName[32] = "spots[x].pos\0";
		char innerName[32] = "spots[x].inner\0";
		char radiusName[32] = "spots[x].radius\0";

		posName[6] = '0' + i;
		innerName[6] = '0' + i;
		radiusName[6] = '0' + i;
		
		spots[i].posLoc = GetShaderLocation(spotShader, posName);
		spots[i].innerLoc = GetShaderLocation(spotShader, innerName);
		spots[i].radiusLoc = GetShaderLocation(spotShader, radiusName);
		
	}
	
	// tell the shader how wide the screen is so we can have
	// a pitch black half and a dimly lit half.
	{
		unsigned int wLoc = GetShaderLocation(spotShader, "screenWidth");
		float sw = (float)GetScreenWidth();
		SetShaderValue(spotShader, wLoc, &sw, UNIFORM_FLOAT);
	}

    // randomise the locations and velocities of the spotlights
    // and initialise the shader locations
    for (int i = 0; i < MAXSPOT; i++)
    {
		
		spots[i].pos.x = GetRandomValue(64, screenWidth - 64);
		spots[i].pos.y = GetRandomValue(64, screenHeight - 64);
		spots[i].vel = (Vector2){ 0, 0 };
        
		while ((fabs(spots[i].vel.x) + fabs(spots[i].vel.y)) < 2)
        {
			spots[i].vel.x = GetRandomValue(-40, 40)/10.0;
			spots[i].vel.y = GetRandomValue(-40, 40)/10.0;
		}
		
		spots[i].inner = 28 * (i + 1);
		spots[i].radius = 48 * (i + 1);
		
		SetShaderValue(spotShader, spots[i].posLoc, &spots[i].pos.x, UNIFORM_VEC2);
		SetShaderValue(spotShader, spots[i].innerLoc, &spots[i].inner, UNIFORM_FLOAT);
		SetShaderValue(spotShader, spots[i].radiusLoc, &spots[i].radius, UNIFORM_FLOAT);
	}

    SetTargetFPS(60);               // Set  to run at 60 frames-per-second
    //--------------------------------------------------------------------------------------
    
    // Main game loop
    while (!WindowShouldClose())    // Detect window close button or ESC key
    {
        // Update
        //----------------------------------------------------------------------------------
        frameCounter++;

		// Move the stars, resetting them if the go offscreen
        for (int n = 0; n < numStars; n++) UpdateStar(&stars[n]);

		// Update the spots, send them to the shader
		for (int i = 0; i < MAXSPOT; i++)
        {
			if ( i == 0 ) {
				Vector2 mp = GetMousePosition();
				spots[i].pos.x = mp.x;					
				spots[i].pos.y = screenHeight - mp.y;
			} else {
				spots[i].pos.x += spots[i].vel.x;					
				spots[i].pos.y += spots[i].vel.y;
				
				if (spots[i].pos.x < 64) spots[i].vel.x = -spots[i].vel.x;					
				if (spots[i].pos.x > screenWidth - 64) spots[i].vel.x = -spots[i].vel.x;					
				if (spots[i].pos.y < 64) spots[i].vel.y = -spots[i].vel.y;					
				if (spots[i].pos.y > screenHeight - 64) spots[i].vel.y = -spots[i].vel.y;
			}
			
			SetShaderValue(spotShader, spots[i].posLoc, &spots[i].pos.x, UNIFORM_VEC2);				
		}
			
        // Draw
        //----------------------------------------------------------------------------------
        BeginDrawing();

            ClearBackground(DARKBLUE);

			// Draw stars and bobs
            for (int n = 0; n < numStars; n++)
            {
				// Single pixel is just too small these days!
                DrawRectangle(stars[n].pos.x, stars[n].pos.y, 2, 2, WHITE);
            }

            for (int i = 0; i < 16; i++)
            {
                DrawTexture(texRay,
                    (screenWidth/2.0) + cos((frameCounter + i*8)/51.45f)*(screenWidth/2.2) - 32,
                    (screenHeight/2.0) + sin((frameCounter + i*8)/17.87f)*(screenHeight/4.2),
                    WHITE);
            }

			// Draw spot lights
			BeginShaderMode(spotShader);
				// instead of a blank rectangle you could render here
				// a render texture of the full screen used to do screen
				// scaling (slight adjustment to shader would be required
				// to actually pay attention to the colour!)
				DrawRectangle(0,0,screenWidth,screenHeight,WHITE);
			EndShaderMode();

            DrawFPS(10, 10);
            
            DrawText("Move the mouse!", 10, 30, 20, Color::GREEN);
            DrawText("Pitch Black", screenWidth * .2, screenHeight / 2, 20, Color::GREEN);
            DrawText("Dark", screenWidth * .66, screenHeight / 2, 20, Color::GREEN);
            

        EndDrawing();
        //----------------------------------------------------------------------------------
    }

    // De-Initialization
    //--------------------------------------------------------------------------------------
    UnloadTexture(texRay);

    CloseWindow();        // Close window and OpenGL context
    //--------------------------------------------------------------------------------------

    return 0;
}


void ResetStar(Star *s)
{
    s->pos = (Vector2){ GetScreenWidth()/2.0f, GetScreenHeight()/2.0f };
    
    do
    {
        s->vel.x = (float)GetRandomValue(-1000, 1000)/100.0f;
        s->vel.y = (float)GetRandomValue(-1000, 1000)/100.0f;
        
    } while (!(fabs(s->vel.x) + fabs(s->vel.y) > 1));
    
    s->pos = Vector2Add(s->pos, Vector2MultiplyV(s->vel, (Vector2){ 8, 8 }));
}

void UpdateStar(Star *s)
{
    s->pos = Vector2Add(s->pos, s->vel);
    
    if (s->pos.x < 0 || s->pos.x > GetScreenWidth() ||
        s->pos.y < 0 || s->pos.y > GetScreenHeight())
    {
        ResetStar(s);
    }
}


